CHARLES WOOLEY: I'm on a remote stretch of southern English beach - the last person Chloe McCardel can touch or even speak to before she embarks on her grand passion.

CHLOE: I think I’m just addicted to the challenge. There’s nothing like swimming the English Channel as a way to challenge yourself physically, mentally, challenge how well prepared you are for an athletic event. It really is the pinnacle of marathon swimming.

CHARLES WOOLEY: But that challenge can take its toll. Before it’s over, this brave young woman might just push herself too far. Three days earlier, high and dry, on English soil with Chloe McCardel from Melbourne – one of that rarest breed of long-distance swimmers who abandon the safety of the pool for the danger of the wild ocean. And for such people, this is the only place in the world to be. Now that’s it – that’s France, we can see it.

CHLOE: Yeah and just to the right, well you can’t quite see it now, but that is Cape Gris Nez with those rocks and the lighthouses where I am hoping to hit. It’s the shortest route to France.

CHARLES WOOLEY: Standing here it looks a long way.

CHLOE: It’s even longer when you’re trying to swim it.

CHARLES WOOLEY: At 26, Chloe is already a hardened veteran of the Channel. A single crossing in 2009 and then a France-and-return double crossing success last year.

TRAINER: OK Chloe, keep your chest up, shoulders back.

CHARLES WOOLEY: And for the past year, she’s been training all over Australia for this year’s marathon attempt…

TRAINER: Make the biggest bicep, ready!

CHARLES WOOLEY: …Three crossings without a break. A feat hundreds have tried, but only three have ever achieved. Statistically, it’s much harder than climbing Everest.

TRAINER: Chloe, I’m just going to check your core temperature.

CHARLES WOOLEY: To swim the English Channel, you need to have such a strong goal in your head and have that mental strength. I just thrive on the challenge and difficulty of such an event.

CHARLES WOOLEY: Husband Paul McQueeney, her number one supporter, is happy to see his wife putting on weight. The body fat will help her survive the freezing water.

CHARLES WOOLEY: She doesn’t say much at lunch, does she? As a marathon swimmer himself, Paul knows all too well the demands of a Channel crossing.

PAUL: Yeah, I think having crossed the Channel myself, then having lived through Chloe’s double crossing last year, I think I understand the pain of what’s required to do this enormous task that she’s taken on. I mean, you’re talking 140, 150 kilometres in 15 degree water, 33 hours of swimming. I challenge them to just stay awake for 34 hours.

CHARLES WOOLEY: Well into the first leg and Chloe’s a strong performer. Beautiful out of the water, stupendous in it. Like a superbly-adapted amphibious creature, she glides through the water, perfect stroke after effortless stroke. Now in her first crossing, Chloe will take 50,000 freestyle strokes, and breathe 22,000 times, all under the watchful eye of her boat-bound support crew.

CHLOE: I get really into a zone where I can focus on what I need to do and that’s enough to keep me happy and content swimming along.

CHARLES WOOLEY: But Chloe isn’t alone in her passion. The Channel holds an almost mystical allure and right now, it’s peak season for channel challengers. Hopefuls from all over the world, driven by the same obsessive determination to swim to France. Well, ihis is Shakespeare Beach in Dover, and of course Shakespeare described the English Channel as ‘a moat defensive against the envy of less happy lands.’ Certainly, the Channel stopped the Spanish Armada, it stopped Napoleon and it stopped Hitler. But this week, 300 people will try to swim across it and again, it will stop most of them. 90% will fail, because the Channel still rules. They may not be beaches by our standards, but the Brits do love to be beside the seaside, no matter what the weather.

FRIDA: It’s a nice dry morning at the moment but I’ll give you a clue – if it’s wet like last week, ain’t going to be nobody here on the beach or when you get out!

CHARLES WOOLEY: Frida Streeter is a grandmother and volunteer trainer who’s watched the contenders come and go and believes they all have one thing in common. They’re mad.

FRIDA: I think it’s crazy, I think it’s crazy.

CHARLES WOOLEY: You think it’s crazy?

FRIDA: Yeah, I do. You know, I work with them all the time, and I keep saying, “you know, over there there’s a ferry, up there there’s an aeroplane, down there is a train.” Why would you want to swim here? It doesn’t make any sense to me, but they come in their droves. It’s the premier swim of the world.

CHARLES WOOLEY: The first crossing’s still going well. With flat seas and the wind at her back, Chloe and her support team are in good spirits.

PAUL: Yeah, I’m very proud of her. She’s doing very well.

CHARLES WOOLEY: She’s a machine!

MURPH: She is a machine, I mean, she does the hard yards. She’s been averaging does over 100 kilometres a week at home in preparation for this. She knows she has three laps to do, and that’s all she’s focusing on.

CHLOE: Oh the first leg, I’m just warming up. I’m excited, yeah, it’s just a lap for me – then the second lap I’m going to have to knuckle down and turn on the after-burners because that’s going to be…that’s going to be tough.

CHARLES WOOLEY: Among Chloe’s on-board support crew is Murph Renford, the look-alike son of Australia’s King of the Channel, Des Renford, who conquered the stretch in 19 single crossings back in the 70s.

MURPH: She’s averaging four kilometres an hour, which for the swimmers that are watching tonight, that’s basically 15 minutes a kilometre. And I can tell you, your average person going to the pool tomorrow morning for their Monday morning session won’t be able to do one kilometre in 15 minutes – and Chloe’s going to average that for over 30 hours.

CHLOE: I’ve never been in that territory before, I’ve never swam for more than 25 hours in cold water continuously. Swimming in 15 degree water is really tough for your body, and to do it for an extended period of time, you know anything more than five or six hours, your body is really fighting against that cold and using up energy to fight the cold water.

FRIDA: They’re so fickle out there. You never know what’s going to happen. Um, it’s never the same two days running. And it is very strange, it has numerous weather patterns out there and anything can happen.

CHARLES WOOLEY: But it doesn’t stop novices like English publican Thomas Noblett from giving it a go. Three years ago you couldn’t swim?

THOMAS: No, not a stroke, about the only thing I could do was put one arm over the other, swim a bit.

CHARLES WOOLEY: How come you got into this kind of madness?

THOMAS: Well it ended up as a bet, then we did more swims, and the sort of pinnacle is to swim the Channel – it’s the Everest of swims.

CHARLES WOOLEY: It’s certainly true. It’s ‘different strokes for different folks’. And weighing in at a tidy 18 stone in his trunks on Dover Beach, Thomas Noblett redefines the athletic dreams of average blokes all around the world.

CHARLES WOOLEY: So you’re doing this for larger men, for beer drinkers all over the world – proving that they can conquer the Channel.

THOMAS: Yes, larger men, and very good looking men actually.

CHARLES WOOLEY: I’ve closed the numbers, I’m giving 10 to one against you.

THOMAS: Yes, and that’s what I like. I like people saying, ‘you’ll never get across there, you’ll never do it’. It is me provin’ them wrong basically.

CHARLES WOOLEY: Do you want to put a fiver on it? Yeah I will. Well Thomas you’re a good bloke, I wish you well.

THOMAS: Oh cheers.

CHARLES WOOLEY: Oh you’re sticky!

THOMAS: Yeah. Just what you ordered!

CHARLES WOOLEY: Meanwhile on the other side of the Channel, Chloe is onto lap two. In mere moments she’s touched the French shore, has tumble-turned and is on her way back.

CHARLES WOOLEY: But the weather is changing. The sea is rising and an unexpected cold front is sweeping down from the North East.

CHLOE: The reason why the Channel is so hard is because there are so many variables you can’t control. You can’t control the wind, the tide, the water temperature, the air temperature…

CHARLES WOOLEY: After 17 hours battling headwinds and a sudden cold snap, Chloe’s in serious trouble. Time and tide wait for no woman. At midnight, grim reality triumphs over ambition. Chloe is floundering in rough seas and making no headway.

PAUL: Keep it going, sweetie.

CHARLES WOOLEY: And it’s time to call an end to this cruel ordeal.

MURPH: Paul and I basically made a joint decision to end the swim, really fearing for her own wellbeing more than anything else.

CHARLES WOOLEY: For me, not even years of reporting could mitigate the sadness of this moment – the cold indifference of the sea smashing this young woman’s dream.

CHARLES WOOLEY: This was a dreadful moment as we carried her away. Did you ever think it would end like this?

PAUL: No, it got a lot cooler than we expected a lot quicker. We probably should have got her out an hour and a half earlier, but she just would not move, would not budge.

CHARLES WOOLEY: She wanted to do it. Chloe’s core body temperature had dropped to just 28 degrees, a level at which most people fall into a coma. Had her obsession pushed her body too far this time?

PAUL: At the end of the day, Chloe’s done a lot longer swims, in the end, it was just one of those freak things that happened. She’s got no idea – still no idea – that we’ve actually pulled her out.

DOCTOR: You’ve done very well. You’ve done remarkably well.

CHARLES WOOLEY: The next morning, we find Chloe in the intensive care unit of Canterbury hospital.

CHLOE: The hypothermia must have hit me really quickly because I, I don’t remember the last few hours of the swim and have been told it today by Paul. All I remember is being happy, swimming in the dark towards England. The lights were quite large, I could even see the shapes of some of the buildings.

CHARLES WOOLEY: Chloe suffered severe hypothermia. Losing consciousness, she breathed in sea water, which damaged her lungs. It was a long night for ICU specialist Dr Gustav Strandvik.

DOCTOR: So it had two effects the hypothermia, which led onto that lung condition which was actually fairly serious overnight. And people who aren’t as fit as you wouldn’t have bounced back so quickly. But she’s not quite there yet, and we’re going to hold her here for a little bit longer until we’re happy that she’s really out of the woods.

CHARLES WOOLEY: I’ll tell you though, it is a great relief to see you the way you are now!

CHLOE: Yeah well, I’m glad I survived so now I can go back and do it again…

CHARLES WOOLEY: No! Oh, No!

CHLOE: Go for another attempt!

CHARLES WOOLEY: Remember publican Thomas Noblett, whom we left all at sea on his way to France? This challenger bravely spent 17 hours battling those same bitterly cold conditions that put an end to Chloe’s hopes. But alas, it wasn’t to be for Thomas either. But likewise, he’s already making plans to return.

THOMAS: It grips you. I call the Channel my mistress. This is my third attempt now. She’s the only other lady in my life and she’s a little bit cruel to me at the moment, but I will tame her.

CHARLES WOOLEY: There aren’t many chances in life these days to take a risk or challenge yourself to the physical limit. So when people do, we scarcely know whether to caution them or applaud them. Like Chloe, I think we should cheer them on.

CHLOE: I’m not quite sure why the average Australian is intrigued about say, extreme sport or pushing the limits. I mean, I can only guess that maybe there’s a part of all of us that would like to be a bit adventurous.